*******Note that forecast and outlooks in this post are NOT the official forecast from the National Hurricane Center (NHC). They are my own detailed views on the Atlantic tropics based on current observations and latest computer model runs. As such do not make decisions based on my posts...consult news media...watches and warnings from your local weather office...and any evacuation orders issued by local governments to make the most informed and best decisions. Visit the NHC website hurricanes.gov (hurricanes dot gov) for the latest watches/warnings and official forecasts on active tropical cyclones.**********
...TUESDAY SEPTEMBER 27 2022 3:03 AM EDT...
Intensifying Hurricane Ian is moving into western Cuba... and threatens the west coast of the Florida peninsula. See Ian section below for more details. In addition to Ian... also monitoring multiple areas of interest as follows:
(1) See area of interest #33 section below for information on a tropical low pressure area expected to meander aimlessly in the eastern tropical Atlantic over the next 12 hours... after which time it will move northwestward into the open central Atlantic. This feature has increased potential to become a tropical cyclone while maintaining signs of organization.
(2) See area of interest #34 section below for more information on a potential tropical disturbance that could materialize offshore of western Africa in the days ahead.
New to this site this year... I will be sequentially numbering up areas of interest for possible Atlantic tropical development. In this scheme... will reset back to #1 at the start of next year (January 2023). The current areas of interest in this blog post is designated #33 and #34 as the other numbers were used in previous birdseye view posts. This scheme is to reduce confusion as Atlantic tropical activity increases during the peak of the hurricane season... when multiple simultaneous areas of interest begin and end which previously required shuffling around the area of interest numbers from update to update.
HURRICANE IAN (RECENTLY UPGRADED TO MAJOR HURRICANE IAN)... Collection of colorized infrared satellite frames documenting Ian's intensification as a category 1 and then category 2 hurricane... from 1400Z Monday September 26 to 0530Z Tuesday September 27:
Ian essentially behaved as predicted on Monday by acquiring hurricane strength and proceeding to briskly strengthen into a category 2 hurricane... all while the center turned on an increasing northward track and passing just west of the Cayman Islands earlier in the day and with the eye now located just southwest of the Isle of Youth of western Cuba as of 11 PM EDT. My updated track forecast listed below accounts for the fact that Ian is centered a touch northwest of my prior forecast. Ian is moving north in response to the surface ridge weakness over the eastern US being generated by the eastern divergent side of a large upper trough in the region. Toward the mid and latter part of the 5-day foreast period... models agree that the upper trough and associated surface ridge weakness will gradually lift northeastward and away... trapping Ian south of a potent surface ridge that builds under the western convergence zone of the amplified departing upper trough. In addition the upper trough is expected to leave behind a cut-off trough over the southeastern US. Ian's northward speed is expected to slow in the 2 to 3 day timeframe...a combination of Ian being embedded in steering upper southerly flow ahead of the leftover cut-off upper trough while the potent surface ridge resists Ian's northward progress. Once the main upper trough and associated blocking surface ridge shift further east by days 4 and 5... a gradual increase in northward forward speed is expected to develop.
Regarding the intensity forecast... Ian is essentially on par with my previous and I continue to predict Ian will peak as a category 3 hurricane in the timeframe that is now 24 hours away. As of this update... I do not anticipate a category 4 peak as the NHC continues to project as the hurricane will begin to encounter potential southwesterly wind shear induced by the southward-digging eastern US upper trough once Ian moves past western Cuba and into the southeastern Gulf of Mexico. As of 11 PM EDT... the thunderstorm core of Ian on colorized-infrared satellite already looked a little stressed from upper southwesterly flow while elongated southwest-to-northeast. There is one caveat though... in the next 24 hours the southwesterly flow on the east side of the upper trough may try to enhance Ian's northern outflow which may aid the hurricane... and so I will increase the intensity forecast in a special update later today should in fact this become the case. However once Ian's core moves into the upper southwesterly flow... the shearing effect of the flow on Ian will increase and I still forecast Ian to begin weakening in the timeframe that is now after 24 hours. The shear will only worsen for Ian as it slows down and falls behind the upper southwesterly wind speed in the 2 to 3 day timeframe. My updated intensity forecast shows a slightly faster decay rate of the previous as the slight northwest adjustment in my track forecast brings Ian into the shearing upper southwesterly flow sooner. For the 96 hour timeframe... as Ian moves into southern Georgia... I only slightly lowered the intensity forecast due to a potential favorable interaction between Ian and the leftover cut-off upper trough over the southeast US. The northerly surface low on Ian's west side may help to pull cool air associated with this trough southward... helping to amplify the trough. An amplifying adjacent warm core central US upper ridge wave to be bolstered by the warm sector of a western US frontal system may also amplify the trough... with increased divergence on the east side of the more amplified trough helping Ian.
Regarding impacts to land areas:
(1) Weather conditions have markedly improved over the Cayman Islands. Coastal sea swells here and along the north coast of the Mexican Yucatan peninsula province of Quintana Roo should decline as Ian lifts northward and away from the region.
(2) Tropical storm force conditions (wind... rain... and coastal sea swells) have overspread western Cuba as of this writing. Strong and potentially life-threatening hurricane-force coastal storm surge and wind for the Isle of Youth... as well as the western Cuban mainland in the vicinity of the isle and over the western tip... will occur in the next few short hours and could very well be already occurring.
(3) For the Florida Keys... the core of what is expected to be a major category 3... possibly a category 4... Hurricane Ian will pass just to the west by this evening. Coastal storm surge and strong wind is anticipated as the eastern core and rain bands of the hurricane pass over... with impacts being most severe in the westernmost keys. I recommend preparations here be rushed to completion.
(4) For the Florida peninsula... the east side of Ian is expected to overspread the area this evening further south... and the entire peninsula by Wednesday. The expected slow down in the forward speed will subject the peninsula to prolonged impacts such as high rainfall totals creating a risk of major flash flooding... do not drive your car into a water-covered roadway if you encounter one. Noting that south Florida has already seen heavy rainfall as upper divergence on the east side of the upper trough steering Ian has taken Ian's moisture and made strong thunderstorm activity over south Florida... and rainfall totals will only worsen with Ian's slowing track! Ian's center is expected to be located just offshore of the west coast of the peninsula... subjecting this side of coastline to a long period of onshore pushing wind and coastal storm surge. Based on the latest forecast track... the largest potential for damage from prolonged exposure to hurricane-force wind and storm surge on the west coast is from the Tampa Bay area and points north. The east side of peninsula could also be near enough to Ian's center to experience tropical storm force gusts with some damage potential... particularly north of Miami all the way to the Florida/Georgia border. Continue preparing now for the above-listed impacts... and I recommend preparations finish by this afternoon.
(5) For the Florida panhandle... expect coastal surf across all of the panhandle... and tropical storm force winds with some damage potential in the eastern half of the panhandle by Wednesday and Thursday. The eastern half of the panhandle may also see a prolonged period of heavy rainfall with significant flash flooding potential due to the storm's forecast slow motion. Prepare now... and finish preparing by early Wednesday at the latest.
(6) Southern Georgia can expect a prolonged period of heavy rainfall with significant flash flooding potential due to the storm's forecast slow motion... as well as tropical storm force winds with some damage potential by late Wednesday through Friday. Prepare now... and finish preparing by Wednesday morning at the latest.
(7) Some heavy rainfall with isolated flash flooding potential is possible for northern Georgia... the Carolinas... and eastern Tennessee this weekend if the current forecast holds.
Update as of 2 AM EDT... Ian is now a top-end category 2 hurricane with 110 mph maximum sustained winds with its eye just west of the Isle of Youth and just south of the western Cuban mainland. Making no changes to my intensity forecast below at this time... however as noted in the above intensity forecast discussion I will compose a special update later today to upgrade the intensity forecast should Ian in fact strengthen faster than shown below.
Update as of 2:30 AM EDT... The latest satellite intensity estimation techniques and aircraft reconnaissance indicate Ian has strengthened further to a category 3 major hurricane with 115 mph maximum sustained winds and 956 mb central pressure. If these trends continue... will issue a special update later this morning to bump up my intensity forecast.
******Infohurricanes.com forecast. Visit hurricanes.gov (hurricanes dot gov) for official forecast***********
0 Hr Position (0000Z Sep 27)...105 mph maximum sustained wind hurricane centered just southwest of the Isle of Youth of western Cuba at 21.3N-83.4W
IOH 24 Hr Forecast (0000Z Sep 28)...120 mph maximum sustained wind major hurricane centered just northwest of the Florida Keys at 25N-83.5W
IOH 48 Hr Forecast (0000Z Sep 29)...100 mph maximum sustained wind hurricane centered just northwest of Tampa Bay Florida at 27.7N-83.2W
IOH 72 Hr Forecast (0000Z Sep 30)...70 mph maximum sustained wind tropical storm centered just norhwest of Tampa Bay Florida and just offshore of the northwestern Florida peninsula at 28.7N-83.2W
IOH 96 Hr Forecast (0000Z Oct 1)...45 mph maximum sustained wind tropical storm centered over the Florida/Georgia broder at 30.5N-83.2W
IOH 120 Hr Forecast (0000Z Oct 2)...Remnant low centered over northeastern Georgia at 32.7N-83W
AREA OF INTEREST #33...After appearing to almost become a tropical depression on Monday morning... the wandering tropical low pressure spin in the eastern Atlantic has seen its thunderstorm activity reduce and become lopsided to the northeast side of the circulation. The above birdseye view chart shows upper-level winds at the 200 mb layer of the atmosphere which is what I normally use to assess wind shear... and it would seem based on this system's current position that it is tucked below the tropical upper ridge axis in the region where shear would be low. However the upper trough to the northeast is also close by... and perhaps it is producing upper southwesterly flow over this system and below the 200 mb layer that is dragging the thunderstorm activity off to the northeast.
Expecting this system to remain generally stationary over the next 12 hours as it is located in a saddle point of conflicting steering between the broad low pressure area to the northeast supported by the aforementioned upper trough and Atlantic surface ridge that for days has been trying to push this system west. After 12 hours... the cold core upper trough feature will weaken while remaining isolated from cold air thanks to the ongoing warm core north Atlantic upper ridge. The upper ridge will also break the weakening trough into a series of upper vortices that retrograde southwestward around the ridge. As the upper trough and associated surface low pressure area to the northeast weakens... the Atlantic surface ridge will finally try to push this system west. However an increasing north angle is depicted in the developing west track as the surface ridge will itself develop a weakness to the northwest as the current frontal system over the eastern US will have moved offshore. And as this system likely becomes a stronger/taller tropical cyclone... the upper southwesterly flow ahead of one of the decaying upper vortices would also coax this system on a more northward track. The upper southwesterly flow is expected to become a detriment to this system in the long range by shearing it. Once this system weakens to a shallow feature under the shear and the surface ridge weakness closes with the departure of the frontal system... the recovering surface ridge should turn the weakening system more westward. This explains the more west angle in track from 96 to 120 hours. Regarding intensity... the NHC still has high 70% odds of tropical cyclone formation... and it still seems reasonable that the current light southwesterly shear should abate in the short-term as the cold core upper trough begins to weaken. Therefore for now... I am continuing with a track and intensity forecast for this system assuming that it will still become a tropical cyclone at some point... but I have lowered the peak intensity as this system failed to become a tropical cyclone on Monday morning. The weakening beyond 48 hours and dissipation by 120 hours is a reflection of this system moving into increasing shearing upper southwesterly flow.
******Infohurricanes.com forecast. Visit hurricanes.gov (hurricanes dot gov) for official forecast***********
0 Hr Position (0000Z Sep 27)...Tropical low centered at 14.5N-35.5W
IOH 24 Hr Forecast (0000Z Sep 28)...40 mph maximum sustained wind tropical storm centered at 14.8N-36W
IOH 48 Hr Forecast (0000Z Sep 29)...60 mph maximum sustained wind tropical storm centered at 16.2N-37.5W
IOH 72 Hr Forecast (0000Z Sep 30)...50 mph maximum sustained wind tropical storm centered at 18.8N-41W
IOH 96 Hr Forecast (0000Z Oct 1)...30 mph maximum sustained wind tropical depression centered at 21.8N-44W
IOH 120 Hr Forecast (0000Z Oct 2)...Dissipating surface trough near 23N-47W
AREA OF INTEREST #34...The NHC TAFB has finally added a tropical wave just offshore of Africa in their surface analysis as of 0000Z. Based on studying METEOSAT satellite imagery over the last few days (https://www.goes.noaa.gov/f_meteo.html)... it appears that the wave is a merger between one that has been just offshore and a second one that recently moved in from 7.5W longitude. Meanwhile a third tropical wave appears to be coming into the mix... located over western Africa in the vicinity of 5W longitude... while having a distinct area of thunderstorms around 2100Z. This third wave is harder to see in more recent satellite pictures as its activity has relaxed in recent hours. Eventually anticipating the recent pile-up of waves in the region resulting in a possible tropical low pressure disturbance offshore of western Africa in the days ahead. Without a cohesive disturbance yet defined in the offshore waters and the third eastern wave coming into the mix... I have delayed the westward acceleration of the possible future offshore disturbance in my updated outlook below. There is potential for such a disturbance to develop due to low shear and upper outflow provided by a persistent tropical upper ridge in the region. However I have set peak odds of development at a low 10% and the more reliable GFS and ECMWF models still do not show development in the region... with the CMC becoming the sole model showing eventual development in the region.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (0000Z Sep 28)...0% chance of tropical cyclone formation (western Africa near 10N-8W)
IOH 48 Hr Outlook (0000Z Sep 29)...0% chance of tropical cyclone formation (western Africa near 10N-12W)
IOH 72 Hr Outlook (0000Z Sep 30)...0% chance of tropical cyclone formation (just offshore of western Africa near 11N-17W)
IOH 96 Hr Outlook (0000Z Oct 1)...10% chance of tropical cyclone formation (eastern tropical Atlantic near 11N-21W)
IOH 120 Hr Outlook (0000Z Oct 2)...10% chance of tropical cyclone formation (eastern tropical Atlantic near 11.5N-26W)
...COMPUTER MODEL SUMMARY...
Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/)
1200Z (Sep 26) CMC Model Run...
**For Hurricane Ian... center moves across western Cuba at 24 hours... circulation passes just west of the Florida Keys at 42 hours... weakens to a tropical storm while continuing north into the Big Bend region of the Florida panhandle at 102 hours... weakens to an inland tropical depression centered over southwestern Georgia at 120 hours.
**For area of interest #33...tropical low remains generally stationary through 36 hours while making a small counter-clockwise loop... subsequently moves northwest reaches 21N-43W at 120 hours
**For area of interest #34... broad tropical low becomes better defined southwest of the Republic of Cabo Verde Islands near 12N-26W at 126 hours... tropical low becomes better organized near 13.5N-38W at 168 hours.
1200Z (Sep 26) ECMWF Model Run...
**For Hurricane Ian... center moves across western Cuba at 24 hours... circulation passes just west of the Florida Keys just before 48 hours... centered just west of Tampa Bay Florida at 72 hours... while making landfall on the northwest coast of the Florida peninsula at 96 hours weakens to a high-end tropical storm... while whirling northwestward weakens further to an inland minimal tropical storm centered over the southern Georgia/Alabama border at 120 hours.
**For area of interest #33... tropical low remains generally stationary through 48 hours while making a small counter-clockwise loop... subsequently the tropical low moves northwest and dissipates near 18.5N-37.8W just after 72 hours.
**For area of interest #34... no development shown
1800Z (Sep 26) GFS Model Run...
**For Hurricane Ian... center moves across western Cuba at 18 hours... center passes just west of the Florida Keys at 27 hours... center slows down and begins to drift northeastward just offshore of Tampa Bay Florida at 60 hours... begins drifting northward and makes landfall on the northwest corner of the Florida peninsula at 93 hours while weakening to a strong tropical storm/minimal hurricane... centered over west-central Georgia at 120 hours as an inland tropical depression.
**For area of interest #33... tropical low remains generally stationary through 45 hours while making a small counter-clockwise loop... subsequently the tropical low moves northwest and weakens to a trough near 17.5N-38.8W at 72 hours.
**For area of interest #34... no development shown
1800Z (Sep 26) NAVGEM Model Run...
**For Hurricane Ian... center moves across western Cuba at 18 hours... center passes just west of the Florida Keys at 30 hours... center drifts northeast into Tampa Bay Florida at 72 hours... located over Georgia/South Carolina border at 120 hours as an inland weakening tropical storm
**For area of interest #33...tropical low drifts northeast to 15N-35W through 48 hours... subsequently turns on a west-northwest drift and reaches 16N-36W at 66 hours while weakening to a trough.
**For area of interest #34... no development shown